Tuna, bonito, and other large fish caught by deep-sea fishing or commercially grown in remote areas have their internal organs and the like removed at the fishery where they were raised or on the fishing vessel where they are caught fish, after which they are cut and frozen or wholly frozen at low temperature into blocks to be preserved and transported to the consuming region in a frozen state.
On the other hand, the whole or cut blocks are conventionally inserted in a bag made of plastic film having low-oxygen gas permeability in a reduced-pressure state as proposed in Patent Documents 1 and 2. The blocks are sealed, the packaging bag or a plurality of the packaging bags packaged in the same manner are stored at low temperature using ice or another cooling agent in a Styrofoam container or the like.
However, a conventional method uses a plastic film having gas barrier properties as a package, uses a Styrofoam container or the like as the wrapping, and stores and transports raw fish. Such a method cannot suppress the proliferation of bacteria and other microorganisms that were present before the raw fish were packaged or that were deposited after packaging, and the freshness of the raw fish cannot be adequately maintained over a long period of time. When the interior of the plastic film bag is degassed using a vacuum packaging machine, the interior of the package is decompressed, whereby drip outflow from, e.g., the raw tuna block is facilitated and this facilitates the occurrence of new bacteria. The same phenomenon occurs in the case of raw meats and the like.    Patent Document 1: Japanese Patent Application Laid Open 2000-335599    Patent Document 2: Japanese Patent Application Laid Open 2006-14630